JP2009531622A - Automatic friction clutch control method - Google Patents

Abstract

The method involves detecting an adjustment position of a clutch actuator or a transferring unit for controlling a friction clutch. The set pressure of the clutch actuator is determined. The clutch torque is changed to a new reference value in a pressure-controlled manner, independent of the characteristics of the set pressure-characteristic curve. The set pressure of the actuator is adjusted to another reference value, which corresponds to the reference value of the clutch torque.

Description

  The present invention relates to an automatic friction clutch that is arranged in a power transmission path between an engine and a transmission of an automobile drive train, is formed to be passively engaged by a spring pressing force, and is intermittently engaged by a hydraulically operated clutch actuator. The present invention also relates to a control method for detecting the operation position x_K of a clutch actuator or a transmission member attached to the clutch actuator and using it for controlling a friction clutch.

  The automatic friction clutch of the above kind is often formed as a dry clutch with at least one clutch disk and a spring pressing mechanism with at least one pressing spring. This structure is particularly complete, is robust and has a short overall axial length. Furthermore, this clutch structure can stop the said motor vehicle reliably by operating a parking brake and inserting a gear based on the use condition fastened in the stationary state where an operating force does not work.

  This friction clutch is disengaged mainly for starting and after gear change, to bridge the difference in speed between the vehicle engine and the transmission input shaft, and to make the gear change smooth, and then engaged under control Is done. In that case, the clutch torque, that is, the torque (clutch capacity) that can be transmitted by the friction clutch at that time is adjusted by a hydraulic or pneumatic clutch actuator.

  The clutch actuator can be formed as a hydraulically operated working cylinder, for example. The operating cylinder is disposed outside the friction clutch, and the operating piston is connected via a release lever to a release bearing supported on a guide sleeve fixed to the housing so as to be axially movable. The release bearing can be in contact with a spring tongue of a pressing spring, for example formed as a diaphragm spring. However, as an alternative to this, the clutch actuator can also be formed as a so-called central clutch release. In that case, an annular working piston of a cylindrical working cylinder fixed to the housing coaxially with the input shaft of the transmission is directly connected to the release bearing.

  In the simplest case, the clutch actuator is formed as a single-acting actuating cylinder having an actuating piston, a pressure chamber and a return spring. Such clutch actuator control includes at least one proportional control valve, in particular a first inlet connected to the pressure pipe, a second inlet connected to the pressureless pipe, and a pressure inlet of the clutch actuator. This can be done easily by means of a three-way electromagnetic control valve with an outlet. However, for this purpose, at least two timing valves, in particular two-way electromagnetic timing valves, each having one inlet connected to the pressure tube or pressureless tube and one outlet connected to the pressure chamber of the clutch actuator, It is also possible to use it.

  Adjustment of a predetermined clutch torque, for example a relatively large starting torque or a relatively small creeping torque, has heretofore been based solely on distance control, i.e. the clutch torque of a friction clutch is adjusted to the clutch actuator or transmission member, e.g. release lever or release bearing. This is done according to a torque characteristic curve expressed as a function of working distance or release distance. For this purpose, the working distance is detected by a distance sensor, and the working pressure acting on the clutch actuator is changed until the desired working distance target value is reached, that is, it is increased from the engaged state and decreased from the disconnected state. In this case, if a deviation between the actual value and the target value of the working distance is recognized, the working pressure is increased or decreased according to the deviation until the deviation is eliminated within a predetermined tolerance.

  In this case, if the actual position of the working distance deviates significantly from the target position due to, for example, the sliding surface between the release bearing and the guide sleeve or the engagement of the release lever joint due to wear, dirt or insufficient lubrication, the clutch A large deviation of the actuator operating pressure from the target position occurs. In order to eliminate this working distance difference, the target pressure corresponding to the target position of the working distance is appropriately excessively controlled in the past, that is, in the pure distance-dependent control. This has the disadvantage of bridging the working distance difference and at the same time over-controlling.

  In this regard, the starting operation seems to be particularly problematic. In the starting operation, the friction clutch starts from a disconnected state, and is engaged in the direction of a desired starting torque by inserting the starting gear, and the operating pressure of the clutch actuator is appropriately reduced. In that case, if a negative working distance difference occurs due to an excessive actual position of the working distance or release distance, the working pressure of the clutch actuator is necessarily set to a value lower than the target pressure corresponding to the desired target value of the clutch torque. The Thus, if the resulting working distance difference is abruptly bridged and the friction clutch is over-controlled and thus over-engaged, a relatively large clutch torque is transmitted for at least a short time. This can lead to an undesired sudden start of the vehicle or an undesired engine stop as well.

  Therefore, the basis of the present invention is to propose a control method for an automatic friction clutch of the type mentioned at the beginning, which enables accurate control of the friction clutch and avoids the above-mentioned drawbacks. .

  In order to solve this problem, it is arranged in a power transmission path between an engine and a transmission of an automobile drive train based on the characteristics of the main claim, and is formed so as to be passively fastened by a pressing force of a spring. A control method for detecting the operation position x_K of the clutch actuator or the transmission member attached to the automatic friction clutch intermittently operated by the operated clutch actuator and using it for controlling the friction clutch is proposed.

  Further on the method, the clutch torque for adjusting to the new target value M_K_soll by detecting the clutch actuator operating pressure p_K and adjusting the clutch actuator operating pressure p_K to the target value p_K_soll corresponding to the clutch torque target value M_K_soll. Changed M_K based on pressure control.

  In this case, the bridging of the pressure difference Δp_K = p_K_soll−p_K_ist is performed continuously when the clutch actuator is controlled by a proportional valve, and an appropriate number of operation pulses when controlled by at least two timing valves. It is done step by step.

  Advantageous and reasonable embodiments and improvements of the method are the object of the dependent claims.

  By adjusting the target value M_K_soll of the clutch torque based on the pressure control, excessive control of the clutch torque of the friction clutch and the disadvantages associated with known control methods are reliably prevented. The specific application range of the pressure-dependent control appropriately conforms to the operating pressure characteristic curve p_K = f (x_K) based on the structure of the friction clutch.

  The change of the clutch torque M_K to the new target value M_K_soll is performed first based on the distance control regardless of the progress of the corresponding operating pressure characteristic curve p_K = f (x_K) of the friction clutch, and the operating distance x_K becomes the target position x_K_soll. Only when approaching can it be done based on pressure control. This is because it generally allows for a faster control sequence.

  Such a control sequence in a friction clutch in which the operating pressure characteristic curve p_K = f (x_K) first rises with an increase of the release distance x_K and then has a relative maximum and then drops again, i.e. does not rise monotonically. It is particularly advantageous to apply Such an operating pressure characteristic curve is typical for a friction clutch in which the pressure spring is formed as a diaphragm spring and does not have an auxiliary compensation spring to offset this effect. In this case, there is only a partial clear relationship between the working pressure p_K and the working distance x_K, and thus the clutch torque M_K, so the adjustment of the target torque M_K_soll is in this case first based on distance control. First, based on the pressure control, near the target position x_K_soll.

  Similarly, in all clutch structures, especially the friction clutch where the operating pressure characteristic curve p_K = f (x_K) does not rise monotonously, the change of the clutch torque M_K to the new target value M_K_soll is first made based on the distance control, It can be performed based on the pressure control only when a large working distance difference Δx_K = xK_soll−x_K_ist is recognized. In this case, if the working distance difference Δx_K = xK_soll−x_K_ist does not appear, the target torque M_K_soll is adjusted based on the distance control as a whole, and the target value x_K_soll of the working distance x_K reaching the predetermined target torque M_K_soll is adjusted. Is done by.

  In contrast, in a friction clutch in which the operating pressure characteristic curve p_K = f (x_K) increases monotonically, the change of the clutch torque M_K to the new target value M_K_soll is unlimited, that is, the target value p_K_soll of the operating pressure p_K is reached from the beginning. Until then, it can be done based on pressure control.

  The operating pressure p_K is preferably detected by a pressure sensor because high accuracy is obtained. The pressure sensor is connected to the pressure chamber of the clutch actuator or a connecting pipe that leads to the pressure chamber of the clutch actuator. As an alternative to this, it is also possible to calculate the operating pressure p_K from suitable measurement and / or control values.

  In the pressure-dependent control of the friction clutch, it is preferable to determine the target value p_K_soll of the operating pressure p_K as a function M_K = f (p_K) of the operating pressure from the characteristic curve of the clutch torque stored in the data storage device. As an alternative to this, the target value p_K_soll of the working pressure p_K is taken as a function M_K = f (x_K) of the working distance from the first characteristic curve of the clutch torque stored in the data storage device and the operation stored in the data storage device It is also possible to determine the function p_K = f (x_K) of the working distance from the second characteristic curve of pressure.

  Further, the target value p_K_soll of the operating pressure p_K is set as a function M_K = f (x_K) of the operating distance from the first characteristic curve of the clutch torque stored in the data storage device, and the second value of the operating pressure stored in the data storage device. The function Δx_K = f (Δp_K) of the change in the working pressure from the characteristic curve of the above, where Δx_K = x_K_soll−x_K_ist, Δp_K = p_K_soll−p_K_ist The pressure p_K_soll can also be adjusted.

  When the working distance difference Δx_K = x_K_soll−x_K_ist is recognized, the target pressure p_K_soll is appropriately over-controlled to reach the target position x_K_soll and the target value M_K_soll of the clutch torque after reaching the target pressure p_K_soll. To do.

  However, in order to avoid the aforementioned drawbacks, such over-control of the target pressure p_K_soll to reach the target position x_M_soll should be carried out with a particularly great delay, only after a predetermined waiting time has elapsed.

  Further, the over-control of the target pressure p_K_soll for reaching the target position x_M_soll should be performed only when a predetermined safety condition is satisfied.

  For example, over-control of the target pressure p_K_soll to reach the target position x_K_soll when the vehicle is stopped or at low speed in this regard can be caused by the operation of the parking brake or the service brake or the accelerator pedal in the direction of high output demands. It can be performed only when an operation is detected. This is because sudden start of the car, unintended acceleration or engine stop can be prevented.

  It is preferable to periodically perform over-control of the target pressure p_K_soll to reach the target position x_K_soll and return the operating pressure p_K to the target pressure p_K_soll each time. This is because the catch that occurs can be resolved very quickly. In this case, it is preferable to increase the number and / or pressure amplitude of the periodic over-control of the target pressure p_K_soll as the working distance difference Δx_K = x_K_soll−x_K_ist increases. In order to actually cause periodic over-control of the target pressure p_K_soll, the proportional valve incorporated in the clutch actuator is operated alternately in the direction, and the pressure increase and pressure reduction timing valves are operated alternately.

  For the purpose of illustrating the invention, drawings are appended to the description.

  A first clutch arrangement 1 for applying the method according to the invention is shown in FIG. There, a friction clutch 2 formed as a single-plate dry friction clutch is arranged in a power transmission path between an engine 3 and a transmission 4 formed as a piston-type internal combustion engine.

  The input side portion of the friction clutch 2 includes a flywheel 6 fixed to the crankshaft 5 of the engine 3 and a pressure plate 8 coupled to the flywheel by a clutch cover 7. The output side portion of the friction clutch 2 includes a clutch disk 9 that is disposed between the flywheel 6 and the pressure plate 8 in the axial direction, and is supported on the input shaft 10 of the transmission 4 so as not to rotate but to move in the axial direction. The friction clutch 2 is fastened in a stationary state with no operating force by a pressing spring 11 formed as a diaphragm spring and disposed between the clutch cover 7 and the pressure plate 8 and is movable in the axial direction to a guide sleeve 12 fixed to the housing. And is intermittently provided by a release bearing 13 that is in contact with the spring tongue on the radially inner side of the pressing spring 11.

  The operation of the release bearing 13 and the adjustment of the desired clutch torque M_K_soll of the friction clutch 2 are performed by a hydraulically operated clutch actuator 14. In this case, the clutch actuator 14 is supported as an axially movable cylinder, and is formed as a single-acting operating cylinder having an operating piston 16 that can be moved against the return force of the return spring by an operating pressure p_K acting on the pressure chamber 15. . The piston rod of the operating piston 16 is connected to the release bearing 13 by a release lever 17 that is pivotally supported on the housing, and the increase of the operating pressure p_K causes the release of the friction clutch 2 and the decrease of the clutch torque M_K. ing.

  Control of the clutch actuator 14 is performed by a control valve 18. The control valve 18 is in this case formed as a three-way proportional solenoid valve with two inlets and one outlet, the first inlet being a pressure pipe 19, the second inlet being a pressure pipe 20 and the outlet being a connecting pipe 21. Is coupled to the pressure chamber 15 of the clutch actuator 14 via

  The control valve 18 is connected to a control device 23 via an electric control line 22 for the control. Thus, the clutch torque M_K is changed by continuously changing the operating pressure p_K of the clutch actuator 14 based on the structure.

  In order to detect the operating position x_K of the operating piston 16 or the release lever 17, a distance sensor 24 is arranged in the area of the piston rod of the operating piston 16. The distance sensor 16 is connected to the control device 23 via the sensor line 25. A pressure sensor 26 is connected to the communication pipe 21 in order to detect the operating pressure p_K of the clutch actuator 14. The pressure sensor 26 is connected to the control device 23 via a sensor line 27. Thus, in principle, distance-dependent control and pressure-dependent control of the friction clutch 2 are possible.

  4 differs from the clutch arrangement 1 according to FIG. 3 in that it is configured as two two-way electromagnetic timing valves with one inlet and one outlet for the control of the clutch actuator 14. The control valves 18a and 18b are provided, but the other structures and arrangement are the same. The inlet of the first timing valve 18 a is connected to the pressure pipe 19 and the outlet thereof is connected to the pressure chamber of the clutch actuator 14 via the communication pipe 21. The inlet of the second timing valve 18 b is connected to the pressure pipe 20 and the outlet thereof is connected to the pressure chamber 15 of the clutch actuator 14 via the communication pipe 21. The two timing valves 18a and 18b are connected to the control device 23 via electric control lines 22a or 22b, respectively. In this case, the clutch torque M_K is changed by a step change in the operating pressure based on the structure.

  The relationship between the clutch torque M_K and the operating pressure p_K and the operating distance x_K is illustrated in the diagram of FIG. 1 for the clutch array 1 of FIG. 3 and the clutch array 1 ′ of FIG. 4. In this case, the working distance x_K is the same as the release distance of the clutch actuator 14 or the release lever 17.

  Since the clutch torque progress M_K = f (x_K) decreases monotonically and the operating pressure progress p_K = f (x_K) increases monotonically, the clutch torque M_K, the operating pressure p_K, and the operating distance x_K are distinct. A relationship exists or is derived. Therefore, the adjustment of the predetermined clutch torque M_K could be performed entirely by pressure control instead of the conventional pure distance dependency control in this case. However, in order to speed up the control process, rough control, that is, control up to the vicinity of the target position x_K_soll of the working distance x_K and / or until a large working distance difference Δx_K = x_K_soll−x_K_ist is first performed by distance control, It is preferable to carry out pressure control for the first time thereafter.

  In this method, the operating pressure characteristic curve p_K = f (x_K) does not increase monotonously as in the case of the friction clutch 2 which has the pressing spring 11 formed as a diaphragm spring but does not have another compensation spring. There are advantages that can be applied. FIG. 2 exemplifies the process of the operating pressure characteristic curve p_K = f (x_K) together with the process M_K = f (x_K) of the clutch torque.

  The two diagrams of FIGS. 1 and 2 clarified how the predetermined clutch torque M_K_soll for starting is adjusted. First, in step 1, the friction clutch is completely disconnected by distance control (a broken line with a right-pointing arrow). Next, the starting gear is inserted, and the friction clutch is in stage 2 (dashed line with left arrow), the actual position x_K_ist of the working distance x_K is near the target position x_K_soll, or a large working distance difference Δx_K = x_K_soll−x_K_ist is recognized Until it is done, it is first fastened by distance control.

  Next, the subsequent control of the clutch operation is performed by pressure control by adjusting the target pressure p_K_soll corresponding to the target torque M_K_soll by the clutch actuator 14 in Step 3. If the working distance difference Δx_K = x_K_soll−x_K_ist exists after reaching the target pressure p_K_soll, the target pressure p_K_soll is excessively controlled in order to reach the target position x_K_soll in Step 4.

  This over-control of the target pressure p_K_soll is carried out as a cyclic pressure change and avoids an undesired over-control of the working distance x_K_soll and the clutch torque M_K_soll caused by, for example, a sudden release of the release bearing 13 on the guide sleeve 12 Therefore, it is preferable to return the operating pressure p_K to the target pressure p_K_soll each time.

FIG. 3 shows a diagram of the relationship between the clutch torque of a friction clutch and the operating pressure and operating distance of the corresponding clutch actuator. FIG. 7 shows a diagram of the relationship between the clutch torque of another friction clutch and the operating pressure and operating distance of the corresponding clutch actuator. 1 shows a first clutch arrangement for applying the method according to the invention. Fig. 2 shows a second clutch arrangement for applying the method according to the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Clutch arrangement | sequence 1 'Clutch arrangement | sequence 2 Friction clutch 3 Engine 4 Transmission 5 Crankshaft 6 Flywheel 7 Clutch cover 8 Pressure plate 9 Clutch disc 10 Input shaft 11 Pressing spring 12 Guide sleeve 13 Release bearing 14 Clutch actuator 15 Pressure chamber
Reference Signs List 16 Actuating Piston 17 Release Lever 18 Control Valve 18a Control Valve 18b Control Valve 19 Pressure Pipe 20 Non-Pressure Pipe 21 Connecting Pipe 22 Control Line 22a Control Line 22b Control Line 23 Controller 24 Distance Sensor 25 Sensor Line 26 Pressure Sensor 27 Sensor Line
M_K Clutch torque
M_K_ist Actual torque, M_K actual value
M_K_soll Target torque, target value of M_K
p_K Working pressure
p_K_ist Actual pressure, actual value of p_K
p_K_soll Target pressure, target value of p_K Δp_K Change in operating pressure
S1 Stage 1
S2 Stage 2
S3 Stage 3
S4 Stage 4
x_K Working distance, working position
x_K_ist actual position, actual value of x_K
x_K_soll Target position, x_K target value Δx_K Working distance difference, working distance change

Claims (17)

It is arranged in the power transmission path between the engine (3) and the transmission (4) of the automobile drive train and is formed to be passively fastened by the pressing force of the spring, and is intermittently connected by the hydraulically operated clutch actuator (14). In a control method of detecting an operation position x_K of a clutch actuator (14) or a transmission member attached to the clutch actuator (14) of the automatic friction clutch to be used for controlling the friction clutch
Further, the operating pressure p_K of the clutch actuator (14) is detected, and the operating pressure p_K of the clutch actuator (14) is adjusted to the target value p_K_soll corresponding to the target value M_K_soll of the clutch torque, thereby adjusting to the new target value (M_K_soll). The clutch torque M_K for changing is performed based on pressure control.   2. The method according to claim 1, characterized in that the clutch torque M_K is changed to a new target value M_K_soll based on the distance control first, and only based on the pressure control when the working distance x_K approaches the target position x_K_soll. .   The clutch torque M_K is changed to a new target value M_K_soll based on the distance control first, and only when a large working distance difference Δx_K = x_K_soll−x_K_ist is recognized, based on the pressure control. Or the method of 2.   The change of the clutch torque M_K to the new target value M_K_soll is performed based on the pressure control when there is a monotonically increasing operating pressure characteristic curve p_K = f (x_K). Method.   The operating pressure p_K is detected by a pressure sensor (26) connected to a pressure chamber (15) of the clutch actuator (14) or a connecting pipe (21) communicating with the pressure chamber (15) of the clutch actuator (14). The method according to any one of claims 1 to 4.   In the case of pressure-dependent control of the friction clutch (2), the target value p_K_soll of the operating pressure p_K is determined as a function M_K = f (p_K) of the operating pressure from the characteristic curve of the clutch torque stored in the data storage device. The method according to any one of claims 1 to 5.   In the case of pressure-dependent control of the friction clutch (2), the target value p_K_soll of the operating pressure p_K is determined as a function M_K = f (x_K) of the operating distance from the first characteristic curve of the clutch torque stored in the data storage device, and 6. The method according to claim 1, wherein the operating distance is determined as a function p_K = f (x_K) from a second characteristic curve of the operating pressure stored in the data storage device. .   In the case of pressure-dependent control of the friction clutch (2), the target value p_K_soll of the operating pressure p_K is determined as a function M_K = f (x_K) of the operating distance from the first characteristic curve of the clutch torque stored in the data storage device, and The operating pressure change Δx_K = f (Δp_K) (where Δx_K = x_K_soll−x_K_ist and Δp_K = p_K_soll−p_K_ist) is determined from the second characteristic curve of the working distance change stored in the data storage device. Item 6. The method according to any one of Items 1 to 5.   The target pressure is excessively controlled in order to reach the target position x_K_soll if a working distance difference Δx_K = x_K_soll−x_K_ist is recognized after the target pressure p_K_soll is set. The method according to any one of the above.   The method according to claim 9, wherein the over-control of the target pressure p_K_soll for reaching the target position x_K_soll is performed for the first time after elapse of a predetermined waiting time.   11. A method according to claim 9 or 10, characterized in that over-control of the target pressure p_K_soll to reach the target position x_K_soll is performed very slowly.   The over-control of the target pressure p_K_soll to reach the target position x_K_soll is performed only when a predetermined safety condition is satisfied, according to any one of claims 9 to 11 Method.   13. The method according to claim 12, characterized in that over-control of the target pressure p_K_soll to reach the target position x_K_soll at the time of stopping or at low travel speed is only performed when the operation of the parking brake is sensed at the same time.   The over-control of the target pressure p_K_soll to reach the target position x_K_soll when the vehicle is stopped or at a low traveling speed is performed only when the operation of the service brake is sensed at the same time. Method.   The overpressure control of the target pressure p_K_soll to reach the target position x_K_soll at the time of stopping or at a low traveling speed is performed only when the operation of the accelerator pedal in the direction of a high output demand is sensed at the same time Item 15. The method according to any one of Items 12 to 14.   The periodic over-control of the target pressure p_K_soll is performed in order to reach the target position x_K_soll, and the operating pressure p_K is returned to the target pressure p_K_soll each time at that time. The method described.   The method according to claim 16, characterized in that the number of periodic over-controls and / or the pressure amplitude of the target pressure p_K_soll is increased with increasing working distance difference Δx_K = x_Ksoll−x_K_ist.

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